Surface fastener

ABSTRACT

To provide a surface fastener that can be easily produced, is excellent in strength, has necessary engagement force and can withstand the repetition of use.  
     In a surface fastener for achieving mechanical bonding by entanglement or engagement of a pair of engaging elements, at least one of the engaging elements comprises a sheet-like substrate and a plurality of stem bodies disposed as protrusions on the substrate, and each stem body is made of a composite body of a soft and flexible elastic resin material and a hard resin material having high rigidity.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a fastener. More specifically, this invention relates to a mechanical fastener (hereinafter referred to as a “surface fastener”) that establishes mechanical fastening state by surface bonding or engagement. The surface fastener according to the present invention can be advantageously provided as a hook-loop system fastener or a press system fastener (e.g. “Dual Lock™” fastener).

[0002] As is well known, various kinds of surface fasteners have been proposed and have widely been used for bonding, fixing and binding fiber products, plastic products and paper products and for fixing industrial components, electronic components and building materials.

[0003] For example, the surface fasteners marked by Velcro Co. under the trade name “Velcro™” and from Krarey Co. under the trade name “Magic Tape” belong to hook-loop system fasteners, and these surface fasteners have gained a wide application as fasteners for clothes. The Velcro™ fastener comprises a combination of a hook tape having hooks on the surface thereof with a loop tape having loop-like piles on the surface thereof. The loop tape is produced by use of a nylon woven fabric whose warp groups protrude in the shape of loop piles. When the leg portion of each loop is cut in such a fashion as to leave the end portion as an open hook in this nylon woven fabric, there is produced a hook tape. However, since it is necessary to fully exploit a woven fabric technology to produce the Velcro™ fastener, its production process is complicated, is time consuming and invites the increase of the production cost. Since the woven fabric must be processed to produce the Velcro™ fastener, its shear force is not high, and loops and hooks undergo buckling in the course of the repetition of use. Therefore, the fastener must be exchanged at a relatively earlier timing.

[0004] To solve the drawbacks of the hook-loop system fastener, U.S. Pat. No. 5,077,870 discloses a mushroom-shaped hook strip for a mechanical fastener that improves a production rate by use of an extrusion molding technology in place of the woven fabric technology. The hook of this hook strip includes a stem made of a thermoplastic resin and a mushroom-shaped top formed integrally with, and at, an end portion of the stem.

[0005] U.S. Pat. No. 5,393,475 discloses a method and an apparatus for producing a double-face surface fastener by means of integral molding. In this surface fastener, engaging plates having a shape of an inclining stem are integrally formed on both surfaces of a flat sheet-like substrate. This patent employs a method of laminating two kinds of single-side surface fasteners so that the materials of the engaging plates become different on both surfaces of the substrate.

[0006] Here, the conventional technologies will be summarized. It is generally required for the hook-lop system fastener to conduct a plurality of engaging/disengaging operations. To disengage the hook and loop engaging with each other, however, the hook must undergo deformation to a certain extent for peeling the loop without inviting its breakage because the loop does not have a release portion. However, the plastic hook described above has high rigidity of plastic and does not easily undergo deformation. To disengage the hook from the plastic, deformation till the plastic state is required, and the occurrence of deformation or distortion is unavoidable. Once deformation or distortion thus occurs, the hook loses its capacity for engaging once again after the engaging/disengaging operations are repeated only a limited number of times. The plastic hook is often damaged or broken in the course of the repetition of the engaging/disengaging operation. When a plastic having high rigidity is used to avoid such a problem, however, the loop to be used in combination with the hook is damaged or broken, and the fastener likewise loses it capacity of withstanding the repetition of the engaging/disengaging operations.

[0007] It may be possible to use hook made of a soft and flexible elastic material (elastomer) is place of the plastic having high rigidity. The hook obtained in this way is easily deformable, and breakage of the hook itself and breakage of the loop do not occur. However, since the hook is easily deformable, insufficiency of the engagement force is unavoidable.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

[0008] To solve the problems of the prior art technologies described above, the present invention aims at providing a surface fastener that can be easily produced, is excellent in strength, has required engagement force and can withstand the repetition of use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a sectional view showing one form of a hook-loop system surface fastener according to the present invention.

[0010]FIG. 2 is a sectional view showing one form of a hook-like engaging element according to the present invention.

[0011]FIG. 3 is a sectional view showing another form of a hook-like engaging element according to the present invention.

[0012]FIG. 4 is a sectional view showing still another form of a hook-like engaging element according to the present invention.

[0013]FIG. 5 is a sectional view showing one form of a press system surface fastener according to the present invention.

[0014]FIG. 6 is a sectional view showing still another form of a hook-like engaging element according to the present invention.

[0015]FIG. 7 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0016]FIG. 8 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0017]FIG. 9 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0018]FIG. 10 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0019]FIG. 11 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0020]FIG. 12 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0021]FIG. 13 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0022]FIG. 14 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0023]FIG. 15 is a sectional view showing still another structural example of a hook-like engaging element according to the present invention.

[0024]FIGS. 16a and 16 b are schematic views illustrating the outline of a tack peeling force measurement method used in the evaluation test in the examples.

DETAILED DESCRIPTION

[0025] The object of the invention described above can be accomplished by a surface fastener for achieving mechanical bonding by entanglement or engagement of a pair of engaging elements, wherein at least one of the engaging elements comprises a sheet-like substrate and a plurality of stem bodies disposed as protrusions on the substrate, and each of the stem bodies comprises a composite body of a soft and flexible elastic resin material and a hard resin material having high rigidity.

[0026] The surface fastener must have suitable engagement strength and high durability capable of withstanding the repetition of use, but it has been difficult to simultaneously satisfy these requirements as already explained. In the surface fastener according to the present invention, however, one of the engaging elements is shaped into the form of the stem body, and this stem body is made of a material having high rigidity and a soft and flexible elastic material. Since the existence of the portion of the material having high rigidity can improve the engagement strength and the existence of the portion made of the soft and flexible elastic material can improve durability of the fastener to cope with the repetition of use. There can be thus obtained the surface fastener having these two characteristics.

[0027] The surface fastener according to the present invention mechanically combines a pair of engaging elements to establish a planar bonding state. The mechanical bonding form is generally fitting, entanglement or engagement, though various other forms may be employed, whenever necessary. Therefore, the surface fastener according to the present invention can take various forms depending on the engagement form, and can include engaging elements having various shapes and sizes.

[0028] The surface fastener according to the present invention is typically a hook-loop system surface fastener and a press system surface fastener such as “Dual Lock™” system fastener. Each engaging element that constitutes the surface fastener comprises a protrusion (called a “stem body” in this specification) protruding in a Z-direction (thickness-wise direction) from its substrate, typically a hook-like engaging element, and a loop-like engaging element with which the protrusion can engage. In other words, in the surface fastener of this system, mechanical bonding can be acquired as the hook-like engaging element is entangled or engaged with the loop-like engaging element. In the case of the press system surface fastener, two substrates having the same or similar shape are prepared, and mechanical bonding can be established as stem bodies protruding from the respective substrates in the Z-direction, typically the hook-like engaging elements, are mutually hooked or fitted to each other. The detail of such surface fasteners will be explained hereinafter with reference to the accompanying drawings.

[0029] The surface fastener according to the present invention has its feature particularly in that at least one of the pair of engaging elements constituting the fastener is the hook-like engaging element. The shape of the hook-like engaging element can be arbitrarily changed or modified, whenever necessary. However, the hook-like engaging element generally comprises a sheet-like substrate and a plurality of stem bodies disposed as protrusions on the substrate. Preferably, each stem body has a top having a disc shape, a mushroom shape, a key shape, a wedge shape, an arrowhead shape, or the like. For, such a top provides better mechanical engagement with the mating engaging element and permits an easy engaging/disengaging operation.

[0030] In the surface fastener according to the present invention, each stem body must be made of at least two kinds of materials having different properties. Particularly preferably, moldable resin materials are molded to form the stem body. The substrate and the stem body may be molded separately when molding is conducted, but are preferably molded integrally with each other. Suitable molding materials for practicing the present invention are a combination of a soft and flexible elastic resin material and a hard resin material having high rigidity. Therefore, each stem body generally comprises a composite body of such two kinds of resin materials. When the stem body comprises such a composite body, higher engagement strength and other better effects can be acquired than the conventional hook-like engaging elements.

[0031] In the surface fastener according to the present invention, the soft and flexible elastic resin material constituting its stem body is preferably a thermoplastic elastic resin material or in other words, a thermoplastic elastomer. Such a soft and flexible elastic resin material generally has a bending elastic modulus of less than 1,000 MPa when measured in accordance with ISO 178. Examples of the elastic resin material include, though not restrictive, styrene type elastomers such as styrene-butadiene-styrene and styrene-isoprene-styrene, olefin type elastomers such as ethylene-α-olefin copolymers, ester type elastomers, amide type elastomers, urethane type elastomers, vinyl chloride type elastomers, silicone type elastomers, fluorine type elastomers, their alloys and others.

[0032] The hard resin material having a high rigidity used for forming the composite stem body in combination with the elastic resin material described above is preferably a thermoplastic resin having high rigidity. The hard resin material having such a high rigidity generally has a bending modulus of at least 1,000 MPa. Examples of the hard resin material include, though not restrictive, so-called “engineering plastics” as typified by polyethylene terephthalate, polybutylene terephthalate, nylon, polycarbonate, polymethyl methacrylate, polyacetal, polymethylpentene, acrylonitrile-styrene-butadiene, polyphenylene ether, polyphenylene sulfide, so-called “general-purpose resin” as typified by polyethylene (e.g. high density polyethylene), polypropylene, polystyrene, polyvinyl chloride, their alloys, and so forth.

[0033] The combination of these two kinds of resin materials used for forming the stem body in the practice of the present invention is not specifically designated. However, these materials are preferably selected so that chemical affinity of both of them can be improved. For, if chemical affinity is high in these resin materials, their bonding power can be improved. To improve the bonding power of these resin materials, it is recommended to add a compatibility-improving agent to one or both of the resin materials to improve chemical affinity. An example of the suitable compatibility-improving agent is a copolymer consisting of ethylene-propylene block copolymer and copolymers consisting of other multiple components. Though the stem body generally consists of two kinds of resin materials, it is also recommended to use a polymer formed by using, as its principal component, the monomer forming these resin materials between the two kinds of basic resins as a third resin material (binder).

[0034] The resin materials used for forming the stem body may contain various additives, whenever necessary. Examples of suitable additives (agents), though not restrictive, include fillers such as glass fibers and whiskers, flame-retardants, antistatic agents, colorants such as pigments and dyes, age resisters, softening agents, cross-linking agents, and so forth. These resin materials are preferably thermoplastic in order to form the stem body by the injection molding method or the extrusion molding method. However, heat-resistance may be imparted by copolymerizing a silane coupling agent inside the molecules to thus create cross-linkage bonds upon molding.

[0035] According to one preferred aspect of the present invention, there is provided a hook-loop system surface fastener comprising a pair of hook-like engaging elements including a loop-like engaging element and a stem body as a hook. In such a surface fastener, the loop-like engaging element and the hook-like engaging element may be respectively arranged on a surface of different substrates, or on the top and back surface of one common substrate.

[0036]FIG. 1 is a sectional view schematically showing a former example of the hook-loop system surface fastener 10 according to the present invention. The drawing shows the process in which the loop-like engaging element 30 and the hook-like engaging element 20 that are mechanically engaged with each other are disengaged. The loop-like engaging element 30 consists of a substrate 31 and a loop member 32 disposed on one of the surfaces of the substrate 31 and having a large number of loops entangled with one another in a complicated way. The hook-like engaging element 20 consists of a substrate 21 and a large number of hooks 24 disposed on one of the surfaces of the substrate 21. The substrate 21 and the hooks 24 are formed integrally with one another. Each hook 24 comprises a stem body 22 and a top 23. The top 24 shown in the drawing has a mushroom shape. The hook 24 firmly engages with the loop member 32 as its top 23 is caught by the loop of the loop material 32. However, when peeled, the hook 24 can be peeled easily without generating a large peeling noise.

[0037] The loop-like engaging element may have the same construction and the same shape and size as those of loop-like engaging elements that are generally used in the field of the hook-loop system surface fastener. In other words, the loop-like engaging element may generally have a construction in which a loop material is laminated on one of the surfaces of a substrate such as a plastic sheet or a fiber sheet. The loop material may be produced by processing a woven fabric, a non-woven fabric, a knitted fabric or their combination in such a fashion as to possess a large number of loops on the surface thereof. The substrate may have an adhesive layer and mold release paper for protecting the adhesive layer on the other surface (the surface not holding the loop member), whenever necessary.

[0038] The hook-like engaging element may have various forms, shapes and sizes so long as it satisfies the two conditions that the stem body consists of a composite body of the elastic resin material and the hard resin material and that the hook-like engaging element consists of a sheet-like substrate and a plurality of stem bodies disposed as protrusions on the substrate, as described above and as will be hereinafter described in detail.

[0039] The stem body in the hook-like engaging element is generally a circular cylinder having a round cross-sectional shape but may also be a columnar body such as a square pole, a hexagonal pole, etc, whenever necessary. The proximal end portion of such a stem body preferably has a fillet structure. For, both strength and rigidity can be improved and moreover, the resulting molded article can be easily removed from a mold during production.

[0040] To improve the mechanical engagement operation, the top of the stem body preferably has a disc shape, a mushroom shape, a wedge shape or an arrowhead shape. The top having other shape may also be used, whenever necessary.

[0041] The stem body of the hook-like engaging element can be disposed on the substrate in various sizes and in various distribution densities. Basically, however, the size of the stem body and its distribution density are determined in accordance with the condition of the loop-like or hook-like engaging element as its mating member for engagement. In the case of the hook-loop system surface fastener, for example, the size of the individual stem body and its gap (space) are decided by the kind of the loop material and by the shape and the size of the loop.

[0042] Generally, the stem body has a uniform height, preferably from about 0.5 to 5 mm and more preferably from about 1 to 3 mm. The stem bodies are generally arranged with uniform gaps between them. The distance between the centers of the adjacent stem bodies is generally within the range of about 0.5 to 2.5 mm. However, this range is merely one example, and the stem bodies having a greater or smaller height may be used, if necessary. Alternatively, the stem bodies may be arranged with greater or smaller gaps between them.

[0043] In each stem body, the ratio of its diameter to its height may be changed over a broad range. The ratio of the height of the stem body to its diameter is generally and preferably within the range of about 2:1 to 10:1. The ratio of the diameter of the top of the stem body to the diameter of its trunk portion is generally about 1.5:1 to 3:1.

[0044] Each stem body can be arranged on the substrate in an optional pattern. The arrangement pattern of the stem bodies is preferably a square or triangular pattern, and the stem bodies are arranged preferably and uniformly on the entire surface of the substrate. In the case of the press system surface fastener that will be explained next, contrivance is preferably applied to the arrangement pattern lest transverse slide occurs when the hooks are entangled with one another.

[0045] In the surface fastener according to the present invention, the hook-like engaging element can be modified or changed in various ways within the scope of the invention. For example, preferably, the hook-like engaging element may further comprise an adhesive layer on the back surface of the substrate on which it is disposed. More preferably, the adhesive layer is protected by a release paper, or the like.

[0046]FIG. 2 schematically shows an example of the hook-like engaging element equipped with the adhesive layer. The hook-like engaging element comprises a substrate 21 and a large number of hooks 24 disposed on one of the surfaces of the hook-like engaging element 20 in the same way as the surface fastener explained with reference to FIG. 1. Each hook 24 comprises the stem body 22 and the top 23 having a mushroom shape. An adhesive layer 25 is formed on the surface of the substrate 21 not having the hooks 4. Release paper 26 is laminated on the exposed surface of the adhesive layer 25. Since the adhesive layer is disposed, the engaging element can be fitted more easily to an arbitrary article, and since the release paper is laminated, handling property can be remarkably improved.

[0047] An optional adhesive or tackifier can be used to form the adhesive layer. An example of the suitable adhesive is a hot melt type adhesive, for example, JET-Melt™ EC-3748. An example of a suitable tackifier is an acrylic type tackifier such as SK-Dyne (product of Soken Kagaku K. K.). To improve the bonding strength of the adhesive layer to the surface of the substrate, a corona discharge treatment or a primer treatment may be applied to the substrate surface. Alternatively, an embossing treatment or a sand blast treatment may be applied to increase the surface area.

[0048] The hook-like engaging element may be as such used in the presence, or absence, of the adhesive layer, or may be used in combination with a suitable member. In the case of the application to clothes, for example, the hook-like engaging element may be bonded to a suitable position by utilizing the adhesive layer, or may be sewn to suitable positions by using a sewing thread in place of the adhesive. Further, in the case where the strength, etc, seems insufficient as the hook-like engaging element is as such used, a reinforcing member and other member are further applied to the back surface of the substrate, and the hook-like engaging element is then bonded or sewn to suitable positions. This method can be utilized effectively when sewing is employed to fit the hook-like engaging element to fiber products, for example.

[0049]FIG. 3 schematically shows an example of a hook-like engaging element equipped with a reinforcing member. The hook-like engaging element 20 comprises a substrate 21 and a large number of hooks 24 disposed on one of the surfaces of the substrate 21 in the same way as the fastener explained with reference to FIG. 1. Each hook 24 comprises the stem body 22 and the top 23 having a mushroom shape. A reinforcing member 27 is provided to the surface of the substrate 21 not having the hooks 4 in accordance with the present invention. In the surface fastener according to the present invention, the hook-like engaging element is made of the elastic resin material and the hard resin having high rigidity. Therefore, the elastic resin material can make up for insufficiency of the tear strength as the drawback of the hard resin material, and can effectively prevent the tear resulting from holes generated by sewing. It has been found out, however, that when the reinforcing member is further used in combination according to the present invention, the tear strength can be further improved. Examples of the suitable reinforcing member include webs made of a fiber, such as a woven fabric, a non-woven fabric, a knitted fabric, or their combination. These reinforcing members can be applied generally and advantageously by a laminate processing to one of the surfaces of the substrate. For example, the reinforcing member is inserted simultaneously with the material of the hook-like engaging element, or before and after shaping of the hook-like engaging element, whenever necessary, during shaping of the hook-like engaging element. In this way, the reinforcing member can be laminated by a simple method. Needless to say, other bonding means using the adhesive, etc, may be used to laminate the reinforcing member.

[0050] Furthermore, it is also preferred to apply a loop material to the surface opposite to the surface having the hooks of the reinforcing member, in combination with the reinforcing member because a double-face surface fastener having the hook-like engaging elements on one of the surfaces and the loop-like engaging elements on the other surface can be provided. Such a double-face surface fastener is cut into rectangles and can be advantageously utilized as bonding belts.

[0051]FIG. 4 schematically shows an example of the double-face surface fastener according to the present invention. It can be easily understood that in the surface fastener 20, the loop member 32 and the hook 24 each is disposed on a top or back surface of the substrate 21. Note that the reinforcing member described above is not shown in the drawing, but the conjoint use of the reinforcing member is generally advantageous from the aspects of processability and handling property.

[0052] According to still another preferred aspect of the present invention, there is provided a press system fastener comprising of a pair of hook-like engaging elements each having a stem body as a hook. In such a surface fastener, the hook-like engaging elements may be disposed on the surface of different substrates, or may be disposed on the top and back surfaces of one substrate to constitute a double-face surface fastener.

[0053]FIG. 5 is a sectional view schematically showing the former example of the press system surface fastener according to the present invention. In this surface fastener 10, two hook-like engaging elements 20 having the same construction are fitted through the hooks 24. Each hook-like engaging element 20 comprises a substrate 21 and a large number of hooks 24 disposed on one of the surfaces of the substrate 21 in the same way as the surface fastener explained with reference to FIG. 1. Each hook 24 comprises the stem body 22 and the top 23 having a mushroom shape. As explained with reference to FIG. 2, the hook-like engaging element 20 may further comprises a reinforcing member on the back surface of the substrate 21 on which the hooks 24 are disposed. As explained above, the reinforcing member preferably comprises the web made of fibers such as a woven fabric, a non-woven fabric, a knitted fabric or their combination. The hook-like engaging element 20 may comprise an adhesive layer and, whenever necessary, release paper, on the back surface of the substrate 21 on which the hooks 24 are disposed.

[0054]FIG. 6 is a sectional view schematically showing the latter example (double-face surface fastener) of the press system surface fastener according to the present invention. This surface fastener 10 has a group of hooks 24 on both surfaces of the substrate 21 in such a fashion as to oppose one another. Each hook 24 has the same structure comprising the stem body 22 and the top 23 having a mushroom shape. The surface fastener 10 shown in the drawing uses the hooks 24 having the same structure, but the shape and the arrangement density of the hooks 24 and furthermore, the constituent material of the hooks itself, may be changed so as to control respective engagement force. When permanent bonding is required on one of the surfaces of the surface fastener, for example, the hooks on the surface may be made only of the material having high rigidity.

[0055] In the surface fastener according to the present invention, the stem body constituting at least one of the engaging elements is made of the composite body of the soft and flexible elastic resin material and the hard resin material having high rigidity. The combination of the elastic resin material and the hard resin material inside each stem body is not limited particularly, but may be changed in various ways within the range in which the function and effect of the present invention can be obtained.

[0056] For example, each stem body may be a composite body having a two-layered structure of a center material and an outer cladding material encompassing a substantial portion of the outer periphery of the center material. In the case of such a composite body having the two-layered structure, the center material is preferably the elastic resin material and the outer cladding material preferably is the hard resin material. Alternatively, it is preferred that the center material is made of the hard resin material and the outer cladding material is made of the elastic resin material.

[0057] According to still another aspect, each stem body preferably comprises a trunk portion made of the hard resin material and the top made of the elastic resin material.

[0058] According to still another aspect of the present invention, each stem body may be a composite body having a three-layered structure having a center material, an intermediate material serially covering a substantial portion of the outer periphery of the center material and an outer cladding material. In the composite body having such a three-layered structure, it is preferred, for example, that the center material and the outer cladding material are made of the hard resin material and the intermediate material, the elastic resin material.

[0059] FIGS. 7 to 15 are sectional views each showing a preferred structural example of the hook-like engaging element (hook portion) according to the present invention. Note, however, that the examples shown in these drawings are merely illustrative but in no way limit the scope of the present invention.

[0060] In the hook 24 shown in FIG. 7, the center member is made of the elastic resin material 41 and the outer cladding member encompassing the center member is made of the hard resin material 42. The elastic resin material 41 occupies substantially the whole of the stem body of the hook 24, and the top having the mushroom shape is also made of the elastic resin material 41. Since the top is made of the elastic resin material 41, the fastener can be used repeatedly without inviting breakage of the hook 24. The elastic resin material 41 can constitute the base member of the hook-like engaging element, and a backing layer can be formed on the opposite surface of the substrate to the hook 24 by use of the hard resin material 42.

[0061] In the hook 24 shown in FIG. 8, the center member is made of the hard resin material 42 and the outer cladding member encompassing the center member and the top are made of the elastic resin material 41. Since the elastic resin material 41 occupies the skeletal structure of the hook 24, hooks 24 having stiffness can be obtained. Since the top is also made of the elastic resin material 41, the fastener can be used repeatedly. The hard resin material 42 can constitute the substrate member of the hook-like engaging element, and a backing layer of the elastic resin material 41 can be formed on the opposite surface of the substrate member to the hook 24.

[0062] In the hook 24 shown in FIG. 9, the trunk is made of the hard resin material 42 substantially as a whole, and the top fitted to the trunk is made of the elastic resin material 41. The function and effect of the present invention can be similarly obtained when the materials of the hook 24 are separately used as in this example.

[0063] The hook 24 shown in FIG. 10 represents a modified example of the hook 24 shown in FIG. 9. The trunk of the hook 24 is made of the hard resin material 42 substantially as a whole, and the top fitted to the trunk is made of the elastic resin material 41. The elastic resin material covers the trunk made of the hard resin material 42 as a lower outer cladding member. The outer cladding member imparts suitable flexibility to the hook 24.

[0064]FIG. 11 shows an example of the hook constituted in the form of a three-layered composite body. The center member and the outer cladding member of the hook 24 are made of the hard resin material 42, and the intermediate member sandwiched between the center member and the outer cladding member, and the top, are made of the elastic resin material 41. Since the hook 24 is the composite body, it can acquire the synergistic effect of the hooks 24 shown in FIGS. 7 and 8.

[0065] When modification (that is, the decrease of the height of the center member made of the hard resin material 42) shown in FIG. 12 is applied to the hook 24 consisting of the three-layered composite body, the increase of flexibility due to the increase of the elastic resin material can be accomplished.

[0066] The hook 24 shown in FIG. 13 has a hook-shaped top in place of the top having the mushroom shape in the hook 24 shown in FIG. 7. This hook 24, too, can be produced easily in the same way as the hooks having other constructions, and can provide satisfactory mechanical engagement and other effects.

[0067] The hook 24 shown in FIG. 14 has a wedge-shaped top in place of the top having the mushroom shape in the hook 24 shown in FIG. 7. This hook 24, too, can be produced easily in the same way as the hooks having other constructions, and can provide satisfactory mechanical engagement and other effects.

[0068] The hook 24 shown in FIG. 15 represents a modified example of the hook 24 shown in FIG. 8. In this hook 24, the distribution of the hard resin material 42 that constitutes the center member is limited to only the lower part of the trunk. Therefore, flexibility resulting from the elastic resin material 41 can be effectively improved.

[0069] Incidentally, the sectional views of FIGS. 7 to 15 represent the section of each hook when it is cut and observed at its center portion in the longitudinal direction. It should be understood, therefore, that a part of the resin materials does not appear in some cases in the drawings depending on the mode of the arrangement of the respective resin materials.

[0070] The surface fastener according to the present invention can be produced easily and correctly by means such as an injection molding method, an extrusion molding method, and so forth, and can avoid the drop of the production yield due to the production of defective products. For ready reference, the surface fastener of the present invention can be executed advantageously by use of the web production methods described in PCT Publications WO99/17630 and WO99/17631.

EXAMPLES

[0071] Subsequently, the present invention will be explained with reference to the examples thereof. Note, however, that these examples do not limit the present invention.

Example 1

[0072] In this example, a hook-like engaging element having the sectional shape shown in FIG. 7 and a top having a mushroom shape is produced.

[0073] An ABA 2-kind 3-layer extruder (single screw type, L/D=26/1, diameter=approx. 30 mm) is provided. Polybutylene terephthalate (“Novaduran 5010R7”, a product of Mitsubishi Engineering Plastics Co.) is loaded into an A raw material feed hopper and is supplied to the extruder at a number of revolution of screw of 69 rpm and a cylinder temperature of about 285° C. On the other hand, a polyester elastomer (“Hytrel 15557”, a product of Toray-Du Pont Co.) is loaded to a B raw material feed hopper and is supplied to the extruder at a number of revolution of screw of 35 rpm and a cylinder temperature of about 285° C.

[0074] While being molten, the respective starting resins are extruded onto a roll-like mold from a 2-kind 3-layer die fitted to the distal end of the extruder. Cavities for forming the engaging elements in a stem body density of 140 pcs/cm² are processed into the surface of the mold used hereby, and each cavity can be exhausted by an external vacuum system. Next, the sheet-like molded article immediately after leaving the mold is allowed to pass through a pair of nip rolls. There is thus obtained a web having on the surface thereof the stem bodies corresponding to the cavities of the mold.

[0075] Subsequently, a stainless steel member heated to about 190° C. is pushed to the stem bodies of the resulting web, giving the hook-like engaging elements having a desired shape. In this engaging element, the thickness of the substrate is 0.14 mm, the height of the stem body is 0.35 mm, its diameter is about 0.29 mm and the diameter of the mushroom-shaped top is 0.49 mm.

[0076] The resulting hook-like engaging element (hereinafter called the “sample hook member”) is tested for each of the following evaluation items and in accordance with the following procedures.

Measurement of Shear Strength

[0077] Two stainless steel panels (width: 50 mm, length: 100 mm, thickness: 1 mm) are provided. A loop material available commercially (“Scotchmate SJ3527”, a product of 3M Co.) is cut into a width of 25 mm (effective width: 22 mm) and a length of about 40 mm and is carefully bonded to the surface of one of the panels in such a manner that the edge of the loop material is in registration with that of the panel. The sample hook member is cut into a width of about 30 mm and a length of about 40 mm and is bonded to the surface of the other panel by use of a double-face adhesive in such a manner that the edge of the panel is in registration with that of the sample hook member. These two panels are superposed so that the sample hook member and the loop member entangle with each other in a length of 30 mm. Thereafter, a roller having a weight of 2 kg is allowed to reciprocate once on them. The edge of each panel is clamped by a chuck of a tensile tester (“Instron Model 1122”) and is peeled in a shear direction at a tensile rate of 300 mm/min. A peak value (shear force, N/cm²) at this time is measured. The result of measurement is evaluated in three stages of “good”, “fair” and “no good”. Table 1 shows the results of measurement and evaluation.

Measurement of Tack Peeling Force

[0078] T-shaped jigs (weight: 70 kg) 51 and 52 for peeling the surface fastener after engagement in the perpendicular direction are provided as shown in FIG. 16(A). The area of the bonding surface of these jigs corresponds to the engagement area of the surface fastener and is 30 mm in width and 30 mm in length. A commercially available loop material 32 (“Mechanical Fastener Loop NC-2017”, a product of Sumitoto-3M Co.) is bonded to one 51 of the jigs and the sample hook member 24 is bonded to the other jig 52 by use of a double-face adhesive tape. After bonding is completed, the materials swelling out from the jigs are trimmed in match with the bonding surface of the jigs.

[0079] Next, the sample hook member 24 and the loop member 32 are entangled with each other in such a manner that the jigs do not deviate from each other as shown in FIG. 16(B), and the knob portion of each jig is clamped by the chuck of the tensile tester (“Instron Model 1122”). The gap of the chuck is about 25 mm. The sample hook member 24 and the loop member 32 are peeled in the vertical direction at a tensile rate of 300 mm/min and the peak value (tack peeling force: N/cm²) at this time is measured. Measurement is repeated five times for the same sample hook member and the mean value is determined. The result of measurement is evaluated in three stages of “good”, “fair” and “no good”. Table 1 shows the results of measurement and evaluation.

Defect of Sample Hook Member by Repeated Peeling Test Measurement of Number of Defects

[0080] A BOPP film (#20) is bonded to the tacky surface of a commercially available loop member (“Mechanical Fastener Loop NC-2017”, a product of Sumitomo-3M Ltd.) and is cut into a size of about 10 cm×10 cm. Next, the sample hook member is cut into a size of 30 mm×60 mm. The distal end portion of the sample hook member in the longitudinal direction is nipped by one hand. One of the ends of the loop member is nipped by the other hand. Under this condition, engagement/disengagement of the sample hook member and the loop member is repeated 50 times. In this case, the engagement/disengagement operation is repeated over a broad range lest the engagement portion of both of them causes deviation. After the test is completed, any defect occurring in the sample hook member is observed with eye through a loupe (about 10×). The result of measurement is evaluated in three stages of “good”, “fair” and “no good”. Table 1 shows the results of measurement and evaluation.

Comparative Example 1

[0081] The procedure of Example 1 is repeated with the proviso that a hook-like engaging element having a single composition is prepared in this example for comparison.

[0082] An ABA 2-kind 3-layer extruder (single screw type, L/D=26/1, die diameter=approx. 30 mm) is provided, and polybutylene terephthalate (“Novaduran 5010R7”, a product of Mitsubishi Engineering Plastics Co.) is loaded into each of A and B raw material feed hoppers and is supplied to the extruder at a number of revolution of screw of 55 rpm and a cylinder temperature of about 300° C. Next, the starting resin under the molten state is extruded from a T die fitted to the distal end of the extruder. Subsequently, the sheet-like molded article immediately after leaving the mold is passed through a pair of nip rolls. There is thus obtained a web having on the surface thereof the stem bodies corresponding to the cavities of the mold. Subsequently, a stainless steel member heated to about 210° C. is pushed to the stem bodies of the resulting web.

[0083] The resulting hook-like engaging element is tested about the three items, i.e., (1) shear force, (2) tack peeling force and (3) defect of sample hook member due to repeated peeling in the same way as in Example 1. Table 1 shows the experimental result.

Comparative Example 2

[0084] The procedure of Example 1 is repeated with the proviso that a hook-like engaging element having a single composition is prepared in this example for comparison.

[0085] A polyester elastomer (“Hytrel 5557”, a product of Toray-Du Pont Co.) is loaded into each of A and B raw material feed hoppers of the ABA 2-kind 3-layer extruder (single screw type, L/D=26/1, diameter=approx. 30 mm) and is supplied to the extruder at a number of revolution of screw of 55 rpm and a cylinder temperature of about 300° C. Next, the starting resin under the molten state is extruded from a T die fitted to the distal end of the extruder. Subsequently, the sheet-like molded article immediately after leaving the mold is passed through a pair of nip rolls. There is thus obtained a web having on the surface thereof the stem bodies corresponding to the cavities of the mold. Subsequently, a stainless steel member heated to about 190° C. is pushed to the stem bodies of the resulting web.

[0086] The resulting hook-like engaging element is tested about the three items, i.e., (1) shear force, (2) tack peeling force and (3) defect of sample hook member due to repeated peeling in the same way as in Example 1. Table 1 shows the experimental result.

Comparative Example 3

[0087] The procedure of Example 1 is repeated with the proviso that a hook-like engaging element having a single composition is prepared in this example for comparison.

[0088] A polypropylene (“SRD7-587”, a product of Union Carbide Co.) is loaded into each of A and B raw material feed hoppers of the ABA 2-kind 3-layer extruder (single screw type, L/D=26/1, die diameter=approx. 30 mm) and is supplied to the extruder at a number of revolution of screw of 55 rpm and a cylinder temperature of about 260° C.

[0089] Next, the starting resin under the molten state is extruded from a T die fitted to the distal end of the extruder. Subsequently, the sheet-like molded article immediately after leaving the mold is passed through a pair of nip rolls. There is thus obtained a web having on the surface thereof the stem bodies corresponding to the cavities of the mold. Subsequently, a stainless steel member heated to about 120° C. is pushed to the stem bodies of the resulting web.

[0090] The resulting hook-like engaging element is tested about the three items, i.e., (1) shear force, (2) tack peeling force and (3) defect of sample hook member due to repeated peeling in the same way as in Example 1. Table 1 shows the experimental result. TABLE 1 Example 1 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 (1) Shear force (N/cm²) Shear force 51.5 67.8 22.7 37.1  Judgment Good Good No good Fair (2) Tack peeling force (N/cm²) Peeling force 1.23 2.28 0.13  0.75 Judgement Good Good No good Fair (3) Defects of sample hook due to repeated peeling (number/3 × 3 cm²) Shear force 0 18 0   2* Judgment Good No good Good No good

[0091] From the test results shown in Table 1, the following observation is obtained.

[0092] As to the shear force and the tack peeling force, the numerical value of the sample hook member made of the single composition (elastomer alone) is extremely low. For, the hook member readily falls off from the loop member when disengaged from the loop member after its engagement because the elastomer single substance has low physical strength. In Example 1, in contrast, because the resin having high rigidity improves the physical strength of the sample hook member, the fastener has high numerical values for both shear force and tack peeling force.

[0093] On the other hand, when damage of the sample hook member is observed by repetition of peeling, breakage of the hook member can be observed in the sample hook members (Comparative Examples 1 and 3) in which the sample hook members are made of the resin having high rigidity alone. In Comparative Example 1, the tops of some hook members are observed falling off, and almost all the hook members are turned down from the step portion though the top remains. In contrast, damage of the sample hook member is not at all observed in Example 1.

[0094] As explained above in detail, the present invention can easily produce the surface fastener and can reduce the production time and the production cost. The surface fastener is excellent in strength and does not undergo damage or breakage in the course of repetition of the engagement/disengagement operations. This surface fastener has high engagement force and can withstand the repetition of use.

[0095] The surface fastener according to the present invention can be effectively utilized for various kinds of mechanical fasteners such as hook-loop system fasteners, press system fasteners (for example, Dual-Lock™ system fasteners), and so forth. Since this surface fastener is of the surface bonding type, bonding can be made without shaking and peeling noise. The engagement thickness is small and flexible to such an extent that the engagement portion is not readily noticeable. The surface fastener has high follow-up performance, and a hidden lock system can be applied. Further, design freedom is great. In other words, engagement design can be made without depending on the engagement position and without calling for a space. Furthermore, positioning is easy, and the fastener can withstand the repetition of use and can be easily repaired, too.

[0096] The surface fastener according to the present invention can be advantageously utilized in the fields other than the mechanical field by utilizing its excellent effects described above. For example, the hook-like engaging element can be used as an anti-skid member. In electrophotographic printers, ink jet printers and laser printers, for example, the hook-like engaging element of the present invention can be bonded to a recording sheet conveying system and can conduct a satisfactory paper feeding operation. 

We claim:
 1. A surface fastener for achieving mechanical bonding by entanglement or engagement of a pair of engaging elements, wherein at least one of said engaging elements comprises a sheet-like substrate and a plurality of stem bodies disposed as protrusions on said substrate, and each of said stem bodies comprises a composite body of a soft and flexible elastic resin material and a hard resin material having high rigidity.
 2. A surface fastener according to claim 1, wherein said surface fastener is a hook-loop system fastener comprising pairs of loop-like engaging elements and hook-like engaging elements wherein said stem body forms said hook-like engaging element.
 3. A surface fastener according to claim 2, wherein said loop-like engaging element and said hook-like engaging elements are disposed on opposing surfaces of one substrate.
 4. A surface fastener according to claim 2, wherein said loop-like engaging element and said hook-like engaging elements are disposed on the surfaces of different substrates.
 5. A surface fastener according to claim 4, wherein said hook-like engaging elements further are formed on a substrate which further comprises a reinforcing member on the back surface of said substrate on which said hook-like engaging elements are disposed.
 6. A surface fastener according to claim 4, wherein said reinforcing member is a woven fabric, a non-woven fabric, a knitted fabric or a combination thereof.
 7. A surface fastener according to claim 4, wherein said hook-like engaging element further comprises an adhesive layer on the back of said substrate on which said hook-like engaging elements are disposed.
 8. A surface fastener according to claim 2, wherein said stem body has a top having a disc shape, a mushroom shape, a key shape, a wedge shape or an arrowhead shape.
 9. A surface fastener according to claim 2, wherein said stem body is a composite body having a two-layered structure of a center member and an outer cladding member encompassing a substantial portion of the outer periphery of said center member.
 10. A surface fastener according to claim 9, wherein said center member is made of said elastic resin material and said outer cladding member is made of said hard resin material.
 11. A surface fastener according to claim 9, wherein said center member is made of said hard resin material and said outer cladding member is made of said elastic resin material.
 12. A surface fastener according to claim 2, wherein said stem body comprises a trunk made of said hard resin material and a top made of said elastic resin material.
 13. A surface fastener according to claim 2, wherein said stem body is a composite body having a three-layered structure of a center member, an intermediate member sequentially encompassing a substantial portion of the outer periphery of said center member and an outer cladding member.
 14. A surface fastener according to claim 13, wherein said center member and said outer cladding member are made of said hard resin material, and said intermediate member is made of said elastic resin material. 